1. Field of the Invention
This invention relates to a camera, and more particularly to a camera on which a front converter is mounted in front of a photographing lens in order to elongate a composite focal length of a photographing optical system of the camera.
2. Description of the Prior Art
Various types of front converters are conventionally known which are adapted to be mounted on a photographing lens of a camera for changing an angular field of view of the camera. However, the conventional front converters commonly have drawbacks that (1) they are low in image forming performance of the edge of a picture plane; (2) they have such a large aperture that the compactness of a camera may be deteriorated; and (3) they can attain only a photographing magnification of 1.25 to 1.5 times or so. An attempt to resolve the problems actually required high technique and much expense in designing a front converter lens. Still, a satisfactory result was not attained.
This originates in the fact that even when a photograph is to be taken by a camera on which such a conventional front converter is mounted, a good image of an object for photographing must be formed over an entire photographing picture plane.